Chlorination of organosilicon compositions



June 6, 1950 J. L. SPEER, JR

Paz Yc/a oleo 05e/ m r/ vf Sttnrneps Patented June 6, 1.950

CHLOR'INAT'ION OF RGN'S'IIICO COMPOSITIONS John Leopold Speler, Jr., Pittsburgh, Pa., assignor to Corning Glass Works, -Corning, N. Y.,.-a

corporation of New York Application February 10, 19.47,?-Serial:No.727,629

of va series of products.

siloxane.

:inthe vapor ephase. `r tionz1'eacton..may be accelerated by exposurevof `2i Claims. `l The present invention relates to the Aproduction of organosilicon materials which contain chlorine Vsubstituents in the organic lradicals.

Rob Roy McGregor and Earl 'Leathen Warrickhave disclosed in their copending application -Serial fNo. 647,395, iled February `13, 1946, and

assigned to the'same assignee as the-present invention, the Vchlorination of hexamethyldisiloxane. This chlorination results in the formation chloro derivative.

Zone.

the reaction zone to light,preferablyzsunlightor any other source of high intensity light. Acatalyst may be employed if desired.

The accompanying drawings are flow sheets which illustrate specic-rnodes of operationof the process hereof. Fig. I is a iiow sheet showing operationof the process hereof when conducted as a liquid phase reaction. Fig lII is a-flow sheet showing operation of the process -hereof when The Between the chlorine diffuser The monoclhlorofderival@ conducted asa vapor phase reaction. "tive formed is monochlorrnethylpentamethyldi- In Fig. I, chlorinator I is'connected to fstill1-2 siloxane. Three dichloro derivatives are likewise by line 3 to feed hexamethyldisiloxanefromthe formed. These derivatives are the dichloromethstill to *the chlorinator, and 'by line 4 :to ffeed Vylpentamethyldisiloxane and symmetrical and chlorinated vproduct from chlorinator Ito still 2. unsymmetrical di(chlormethyl) tetramethyldile The 'still 2 is v.provided with -an .inlet 5 .atyits Of lthese four chlorinated .disiloX-anes, upper'end for hexamethyldisiloxane. -Atra mldthe two which are of principal importance co-Inpoint in 'the -lstill there is a trap-out plate "6 Ato mercially are the monoohloro derivative and the trap vdescending liquid Aphase hexarnethyldisiloxsymmetrical dichloro derivative. ane. In' the rzone of the still between/inlet land Objects yof the present invention are to proplate'E/there is provided a calandria 1, arranged vide improved methods for the chlorination of with inlet and-outlet conneCtionsffor cooling-and hexamethyldisiloxana yand to provide methods condensing vaporized lhexa-methylsiloxane. for the chlorination of hexamethyldisiloxane in Alovver Iendofthe stillZ is provided with a non- Which-the normal balance of chlorinatedderivasiphoning overow arranged tomaintain af-body tives is-shifted to give a high yield of the monoof liquid inthe lower end of the still. In the base `of theistill 4there is rprovideda steam coil 9 Inaccordanc'e with the present invention, hexarranged to heat 'the contents of the Alower end iamethyldisiloxane is chlorinated by continually Yofthe s'tillewhereby'to-distill-off hexamethylsiloxcharging -hexamethyldisil'oxane into a Vreaction ane.

Chlorine is also charged continually into Line connects with fthe trap-outplate 6 of the reaction zone, but at a feed rate relative to stil12 to remove liquid phase hexamethyldisiloxthe feed rate of hexamethyldisiloxane sufciently ane therefrom for introduction vinto the chlorinalow to maintainhexamethyldisiloxane in the retor. Line .enters still 2 at a 'point below the action .'zone, continuously. This may be eiected trap-out plateandfab'ove the vlevel of liquidin by'feedin'g the Vchlorine in'amount less than sui- 35 the lower Ipartof still 2. cient to form the rnonochloro derivative. Pref- Chl'orinator I-isa'column which is provided-rin erably less'than 0.5 atom vof chlorine p'er mol 'of its upper end with `a `Calandria Vlil to condense hexamethyldisloxane "is fed into the reaction any hexamethyldisiloxane vapors from hydrogen Chlorinated hexamethyldisiloxane is conchloride which is forrnedin the chlorinatorand tinually removed from the reaction zone. The 40 which `leaves :by outlet vl l at vthe ufpperiendof chlorinated product may be separated, if `de- :chlorinator I. Calandria l!! is vprovidedfvvith suitsir'ed, from unreacted hexamethyldisiloxane. In able inlet and outlet connections for coolant. yA case separation is effected, the separation may chlorinediifuser l2 is positioned in the Vlower end occur either in the reaction zone 'or in a sep- -of chlorinator i. aratezone from which hexamethyldisiloxane may l2 and the liquid level iB in the chlorinator, suitbe recycled tothe reaction zone. By conducting able lights I4 are provided inthe Wall of `the the chlorination in accordance with the method chlorinator ito accelerate the Vreaction as aindistated, a remarkably high proportion ofthe moncated.

ochloro'rderivative is obtained. The lower end of chlorinator i, ata point be- The process of the present invention may be low the chlorine diffuser connects with line 4, conducted under. widely varying conditions. whereby chlorinated product is removedffronrthe Thus, the present process may be conducted as chlorinator. The chlorinator I and Ythe still 2 :aliquid phase reaction, or it may be conducted are positioned at such relative Ylevels that `the The rate of 'the ychlorinainlet of line 4 into still 2 is -at the liquid-level desired in the chlorinator. -Line3 communicates with the chlorinator to deliver hexamethyldisiloxane thereto at a point below calandria l and above liquid level I3.

In operation the temperature of the chlorinator I is maintained at below the boiling point 0f hexamethyldisiloxane, the specific temperature depending upon the particular pressure employed. Temperature control of the chlorinator is eiected primarily by control of heat exchange in calandria 'l and to a minor extent by control of heat lo exchange in Calandria I0. The temperature in the base of still 2 is maintained at a temperature at or above the boiling point of hexamethyldisiloxane at the pressure employed. The temperature likewise should be below the boiling point of the lowest boiling chlorinated derivative, namely, of the monochloro derivative. As the boiling point of the hexamethyldisiloxane and its monochloro derivative diier substantially, no difficulty is encountered in making a clean separation between the two.

While pressure has been referred to, positive pressure above atmospheric is not necessary for the present reaction. Atmospheric pressure is very suitable and the reaction is quite rapid when suitable light or a catalyst is employed. However, if desired, positive pressure above atmospheric may be employed.

In the process as disclosed in Fig. II, the reactants are maintained in vapor phase in the chlorinator 2b. The chlorinator communicates with a distillation column 2l, which serves to separate the monochioro derivative from the small amount of bottoms which is obtained, and which is primarily polychloro derivative. The chlorinator 2@ is provided with three Zones. The top zone of the chlorinator is provided with a Calandria 22 to condense hexamethyldisiloxane vapors rising in the chlorinator in mixture with hydrogen chloride. This top zone is separated from the reaction Zone therebelow by a trap-out plate 23 for removing liquid phase hexamethyldisiloxane from the chlorinator. Spaced from the bottom of the chlorinator 2U there is positioned a plate 24, shaped to drain liquid from the reaction zone into the collector section of the chlorinator therebelow. An inlet 25 for hexamethyldisiloxane communicates with the reaction zone of the chlorinator 2li between the plates 23 and 2li. 'Ihe exact position of the inlet 25 is unimportant. A drain 26 from trap-out plate 23 is provided to remove liquid phase hexamethyldisiloxane. lf desired, this liquid phase hexamethyldisiloxane may be recycled through Vaporizer 2l and line 28 to the inlet line 25. Chlorine maybe introduced by diuser 2li into the reaction zone. Preferably the diiuser 29 is arranged to introduce the chlorine at a multitude of points dispersed throughout the reaction zone in order to prevent high local concentrations of chlorine. Suitable lights 3s are provided in the wall of the reaction Zone of the chlorinator 2Q.

Fractionator 2l is of conventional construction. Line 3l communicates from the lower end of the chlorinator 28 to a mid-point in the fractionator. The level of the inlet into the fractionator is arranged to provide a body of fluid in the base of the chlorinator in order to prevent vapor phase communication of the chlorinator and the fractionating column.

In operation, the feed of hexamethyldisiloxane is sufficient to maintain an atmosphere of the disiloxane in the reaction zone. The chlorine which is introduced thereinto reacts rapidly therewith. While it would be possible to balance the operation and maintain the feed of hexamethyldisiloxane just suiricient that no more is introduced than is adequate to provide a continuous atmosphere thereof, in the reaction Zone, the most eicacious manner of commercial operation involves feeding an excess thereof to chlorinator 20, whereby a portion of the hexamethyldisiloxane is condensed in Calandrial 22 and recycled through lines 2t, 28 and 25.

The reaction zone is maintained at a temperature between the boiling point of hexamethyldisiloxane and of chlormethylpentamethyldisiloxane. Accordingly, upon the chlorination of any portion of the hexamethyldisiloxane, the chlorinated derivative will immediately condense and drop the plate 2t at the lower end of the chlorination zone and then drain into the body of liquid in the lower end of the chlorinator 2i). The chlorinated product then iows from the body of liquid into the fractionator in vwhich the monochloro derivative is separated from the polychloro derivatives.

The following chlorination is illustrative of the present invention.

Hexamethyl disiloxane was fed into the top of a reaction zone, and chlorine gas was fed into the reaction Zone countercurrent to the ow of hexamethyldisiloxane. The chlorine was fed at such a rate that less than 6.5 atom of chlorine was added per mol of hexamethyldisiloxane. The product was continually removed from the zone and fed into the stripping zone. The stripping zone was maintained at a temperature sucient to distill 01T the unreacted heXamethyldisiloXane, which boils at C., and insufficient to distill 01T the monochlormethylpentamethyldisiloxane. The temperature range between these two is about 50 C. The stripping zone was maintained at atmospheric pressure. The hexamethyldisiloxane distillate was condensed and returned to the reaction zone. A distillation analysis of the bottoms products obtained from the stripping zone is as follows:

That which is claimed is:

1. The method of preparing chlorornethylpentamethyldisiloxane which comprises continually charging hexamethyldisiloxane into a reaction zone, continually charging chlorine into said reaction zone in amount less than sucient to form the monochloro derivative of the hexamethyldisiloxane, whereby hexamethyldisiloxane is maintained in the reaction zone continuously, and whereby the hexamethyldisiloxane is chlorinated, and continually removing chlorinated hexamethyldisiloXane from the reaction zone.

2. The method of preparing chloromethylpentamethyldisiloxane which comprises continually charging hexamethyldisiloxane into a reaction zone, continually charging chlorine into said reaction zone in amount less than suicient to form the monochloro derivative of the hexamethyldisiloXane, whereby hexamethyldisiloxane is maintained in the reaction zone continuously, and whereby the hexamethyldisiloxane is chlorinated maintaining the temperature in the reaction zone below the boiling point of hexamethyldisiloxane,

and continually removing hexamethyldisiloxane and chlorinated hexamethyldisiloxane from the reaction zone.

3. The method of preparing chloromethyipentamethyldisiloxane which comprises continually charging hexamethyldisiloxane into a reaction zone, continually charging chlorine into said reaction zone in amount less than suicient to form the monochloro derivative of the hexamethyldisiloxane, whereby hexamethyldisiloxane is maintained in the reaction zone continuously and whereby the hexamethyldisiloxane is chlorinated, maintaining the temperature of the reaction zone rbetween the boiling points of the hexamethyldisiloxane and of the monochloro derivative, Where- 10 by the monochloro derivative condenses upon formation, withdrawing unreacted hexamethyldisiloxane from the reaction zone and separately continually removing chlorinated hexamethyldisiloxane from the reaction zone.

JOHN LEOPOLD SPELER, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,623,018 Cross Mar. 29, 1927 2,348,072 Bailey Feb. 15, 1944 2,384,384 McGregor Sept. 4, 1945 2,386,441 Daudt Oct. 9, 1945 OTHER REFERENCES Krieble, Journ Amer. Chem. Soc, vol. 67 (1945) pages 1810-1812.

Whitmore, Jour. Amer. Chem. Soc., Vol. 68 (1946), pages 481-484.

Krieble et al., Jour. Am. Chem. Soc., vol. 68, pages 2291-2294.v

Certificate of Correction Patent No. 2,510,148 June 6, 195o Y JOHN LEOPOLD SPEIER, JR.

It is hereby certied that error appears in the printed specication of the above numbered patent requiring correction as follows:

Column 27 line 22 and lines 28 and 29, respectively, for hexamethylsiloxene read hexamethyldz'sloxane;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofce. Signed and sealed this 3rd day of October, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant ommz'ssz'oner of Patents. 

1. THE METHOD OF PREPARING CHLOROMETHYLPENTAMETHYLDISILOXANE WHICH COMPRISES CONTINUALLY CHARGING HEXAMETHYLDISILOXANE INTO A REACTION ZONE, CONTINUALLY CHARGING CHLORINE INO SAID REACTION ZONE IN AMOUNT LESS THAN SUFFICIENT TO FORM THER MONOCHLORO DERIVATIVE OF THE HEXAMETHYLDISILOXANE, WHEREBY HEXAMETHYDISILOXANE IS MAINTAINED IN THE REACTION ZONE CONTINUOUSLY, AND WHEREBY THE HEXAMETHYLDISILOXANE IS CHLORINATED, AND CONTINUALLY REMOVING CHLORINATED HEXAMETHYLDISILOXANE FROM THE REACTION ZONE. 